Download MBBS Dermatology PPT 24 Signs In Dermatologyphotodermatology Lecture Notes

Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Dermatology PPT 24 Signs In Dermatologyphotodermatology Lecture Notes

Signs in Dermatology;


Immunobul ous disorders

? The Nikolsky sign ? a firm sliding pressure with the finger separates

normal-looking epidermis from dermis, producing an erosion; also

seen in TEN

? Bulla-spread phenomenon - gentle pressure on an intact bulla forces

the fluid to spread under the skin away from the site of pressure (also

k/a Asboe?Hansen sign, or the "indirect Nikolsky" or "Nikolsky II"

Casal's necklace (Pellagra dermatitis)

? Development of sharply demarcated area of erythema on dorsa of

hands, wrists, forearms, the face & V of the neck (photoexposed parts

of the skin)

? F/B well-demarcated area of pigmentation
? The sharply demarcated lesions on the neck & upper central part of

the chest - known as Casal's necklace


? Button hole sign: Molluscum fibrosum - Small, superficial, soft, skin-

colored to darker, dome-shaped nodules, which can be pushed

through a defect in the skin
? The Crowe sign- Pathognomonic presence of axillary freckling in NF1
? Present in about 30% cases

Carpet tack sign (DLE)

? Characteristic lesion is a well-demarcated, discoid/annular,

erythematous plaque with adherent scales

? When the scale is removed, its undersurface shows keratotic spikes

which have occupied the dilated pilosebaceous canals

? Dermatomyositis ? Characterized by autoimmune inflammatory injury

to striated muscle & skin

? Heliotrope (a lilac-colored flower) erythema: Faint lilac erythema,

periorbitally, usually associated with edema

? Gottron's papules: Violaceous, atrophic papules over the knuckles &

pressure points

? Gottron's sign: Symmetrical, lilac erythema & edema over

interphalangeal or metacarpophalangeal joints, elbows & knees

? Shawl sign: Symmetrical confluent violaceous erythema extending

from dorsolateral aspect of hands, forearms & arms to deltoid region,

shoulders & neck

? Mechanic's hand: Confluent symmetric hyperkeratosis along ulnar

aspect of thumb & radial aspect of fingers

? Grattage test - Scales in a psoriatic plaque can be accentuated by

grating with a glass slide

? Auspitz sign- 3 steps
? Step A: Gently scrape lesion with a glass slide - This accentuates the

silvery scales (Grattage test positive). Scrape off all the scales

? Step B: Continue to scrape the lesion ? A glistening white adherent

membrane (Burkley's membrane) appears

? Step C: On removing the membrane, punctate bleeding points

become visible - positive Auspitz sign

Leprosy (Hansen's disease)

? Cardinal signs
A case of leprosy is a person having one or more of the following three

cardinal signs & who has yet to complete a full course of treatment:
? Hypopigmented or reddish skin lesion(s) with definite

loss/impairment of sensations

? Involvement of the peripheral nerves, as demonstrated by definite

thickening with loss of sensation in the area of distribution

? Positive skin smear for acid - fast bacilli
`Groove sign' of Greenblatt

? Inguinal syndrome (secondary stage) of lymphogranuloma venereum
? Enlargement of the femoral & inguinal lymph nodes separated by the

inguinal ligament

Homan's sign (DVT)

? When symptomatic, onset of DVT is usually acute with swelling, pain

& cyanosis

? Pain worsens on dorsiflexion of foot

? Electromagnetic radiation: any kind of radiation consisting of

alternating electric and magnetic fields and which can be propagated

even in the vacuum

? Solar spectrum consists of electromagnetic (EM) radiations extending


?Very short wavelength cosmic rays
?X-rays & -rays
?Infrared radiation
?Long (wavelength) radio and television waves

UV, Visible & Infrared light

? Light having wavelength b/w 200 - 400 nm ? ultraviolet radiation

(UVR); classified as:

? UVC (200?290 nm): does not reach Earth's surface as it is filtered by

the ozone layer of the atmosphere

? UVB (290?320 nm): 0.5% of solar radiation reaching Earth's surface;

reaches only up to the epidermis; causes sunburn; does not pass

ordinary glass

? UVA (320?400 nm): 95% of solar radiation reaching Earth's surface;

penetrates both epidermis and dermis; causes photoaging & tanning

of the skin; passes through ordinary window glass
? Visible light: Extends between 400 and 700 nm; is part of EM

spectrum perceived by eyes

? Infrared radiation: Extends beyond 700 nm; is responsible for heating



? Etiology: Action spectrum: UVB which induces release of cytokines in

skin, resulting in pain, redness, erythema edema and even blistering

? Skin type: Most frequent and intense in individuals who are skin type

I & II

? Clinical features

? Seen in light skinned

? Areas overexposed to UVR become painful and deeply erythematous

after several hours

? Redness peaks at 24 h and subsides over next 48?72 h, followed by

sheet-like peeling of skin and then hyperpigmentation

? Prevention

? Avoiding overexposure to sun (e.g., sunbathing), especial y by light-skinned


? Using protective clothing and sun shades

? UVB protective sunscreens

? Symptomatic treatment

? Calamine lotion provides comfort

? Topical steroids help, if used early

? Nonsteroidal anti-inflammatory drugs like aspirin relieve pain & also the



? Etiology: Fol owing exposure to UVR, pigmentation occurs in two phases:

? Immediate pigmentation: Occurs within 5 min of exposure to UVA and is

due to:

?Photo-oxidation of already formed melanin

?Rearrangement of melanosomes

? Delayed pigmentation: Begins about 24 h after exposure to both UVB as

wel as UVA; due to:

?Proliferation of melanocytes

?Increased activity of enzymes in melanocytes resulting in increased

production of melanosomes

?Increased transfer of newly formed melanosomes to adjoining

? Clinical features
? Pigmentation following exposure to light occurs in two phases:
? Immediate pigmentation lasts for about 15 min
? Delayed pigmentation lasts for several days
? Degree of pigmentation depends on the constitutional skin color
? Lighter skins burn on UV exposure while darker skins tan


? Etiology
? Photoaging involves changes in epidermis and dermis
? Action spectrum: Epidermis is affected primarily by UVB and dermis

by both UVA and UVB

? Manifestations
? Photoaged skin appears dry, deeply wrinkled, leathery and irregularly


? Comedones are present, especially around the eyes
? Histologically: marked elastotic degeneration
Polymorphic Light Eruption (PMLE)

? Etiology
? Action spectrum: UVA (more frequently incriminated) or UVB (less


? Probably a delayed hypersensitivity to a neoantigen produced by the

action of UVR on an endogenous antigen

? Epidemiology
? Prevalence: Fairly common dermatosis
? Gender: Female preponderance
? Age: Usually in third to fourth decade

Clinical features

? Described as polymorphic eruption, but in a given patient lesions are usually


? Small, itchy, papules, papulovesicles or eczematous plaques on an erythematous


? Develop 2 h to 2 days after exposure to UVR

? Sites of predilection

? Most frequently seen on the sun-exposed areas:

? Dorsae of hands, nape of neck, `V' of chest and dorsolateral aspect of forearms

? Face and covered parts are occasionally involved

? Course

? Recurrent problem, begins in spring and persists through summer

? Photoprotection:

? Avoid exposure to sunlight

? Use of appropriate clothing

? Sunscreens: Important to use UVA sunscreens (i.e., inorganic sunscreens.

Or those containing benzophenones, avobenzone, tinosorb, etc.)

? Symptomatic treatment:

? Topical/systemic steroids, depending on severity

? Antihistamines

? Hardening of skin: With gradual y increasing doses of UVB or PUVA

? Unremitting PMLE: Azathioprine, thalidomide and cyclosporine are useful

? Phototoxic
? Reaction- Non-immunological
? In all individuals exposed to chemical and light in adequate dose
? Photoallergic
? Reaction- Immunological response
? To a photoproduct created from chemical by light
? Occurs in sensitized individuals
? Clinical features
? Phototoxic reactions
? Dose of drug/chemical needed: Large
? Latent period: Reaction immediate (within minutes to hours) after

exposure to light and can occur after first exposure

? Morphology: Initially, there is erythema, edema, and vesiculation
? F/B desquamation and peeling
? Finally the lesions heal with hyperpigmentation (similar to sunburn).

? Photoallergic reactions
? Dose of drug/chemical needed: Small
? Latent period: Reaction occurs on second or third day
? Does not occur on first exposure but after second or later exposures
? Symptoms: Itching often severe. Aggravated after sun exposure
? Morphology: Photoallergic reactions are similar to phototoxic

reactions but are more eczematous
? Investigations
? Phototoxic reactions
? No investigations required
? Photoallergic reactions
? Photopatch tests

? Phototoxic reactions
? Photoprotection
? Withdrawal of drug: Only necessary, if excessive exposure to UVR cannot be avoided
? Symptomatic treatment:
? Topical steroids
? Nonsteroidal anti-inflammatory drugs
? Photoal ergic reactions
? Photoprotection: Very important
? Withdrawal of drug & substitution with a chemical y unrelated drug is essential
? Symptomatic treatment:
? Mild disease: Topical steroids and antihistamines
? Severe disease: Systemic steroids, azathioprine & methotrexate in severe dermatosis
? Solar radiation can be both a `boon' or `bane' to the skin

Thank you

This post was last modified on 07 April 2022